2-loop Antenna Measurement Method for the

Emission Noise Test of Automotive Component

Yasuyuki Matsuda1, Hiroyuki Arai1, Takanori Uno2, Ichiro Akahori2, Toshiyasu Tanaka3 1Graduate School of Engineering, Yokohama National University

79-5, Tokiwadai, Hodogaya-ku, Yokohama-shi, Kanagawa, 240-8501, Japan

matsuda-yasuyuki-dn@ynu.jp, arai@ynu.ac.jp 2DENSO EMC ENGINEERING SERVICE CORPORATION, 1-1 Showa-cho, Kariya-shi, Aichi-ken, 448-8661, Japan

TAKANORI_UNOU@denso.co.jp, ICHIRO_AKAHORI@denso.co.jp 3Microwave Factory Co., Ltd., 3-11-9 Haramachida, Machida-shi, Tokyo, 194-0013, Japan

tanaka@mwf.co.jp

Abstract – CISPR25 test is used to characterize EMC performance of automotive component. To avoid miss detection

of unwanted emission in this test, it is necessary to scan the measurement antenna along the wire. In this paper, we propose a no scanning method using two loop antennas placed near

DUT and wire terminal. Simulation and measurement show that the proposed method picks up unwanted signal with the errors less than 5 dB.

Index Terms — electromagnetic compatibility (EMC), electromagnetic emission, measurement method, CISPR25

1. Introduction

Recent years, number of electronic devices within vehicles

is increasing for improvement of performance by electronic

control. Under such environment, electrical devices are

densely packed and vehicles should be tested to find the

possibility of malfunction by the interference of emission

noise. CISPR25 component-level test [1] is global standard

to evaluate for radiation noise in electromagnetic

compatibility (EMC) test of automotive. Under the test,

radiated emissions may be missed due to the null position of

electric field distributions at measurement probe and the

scanning measurement is required [2]. It can measure exactly

by avoiding the small field position but takes more time for

measurement than CISPR25 test.

We propose 2-loop antenna measurement method to

remove scanning function in emissions test. It consists of two

loop antennas placed near device under test (DUT) and wire

termination, respectively. This paper shows simulated and

measured performance of proposed method.

2. Scanning measurement method

The setup of CISPR25 test is shown in Fig. 1. It consists of

test system (DUT, harness, line impedance stabilization

network (LISN), battery, and metal table) and receiving

antennas (bi-conical antenna in 30-300 MHz and log-

periodic antenna in 300-1000 MHz) placed within an

anechoic chamber whose floor is gland plane. In the

simulation, DUT model is the shield box included a comb

generator as noise source and LISN is 50 Ohm terminator.

Fig. 1 CISPR25 test setup

Fig. 2 Electric field in 400 MHz

The test evaluates at only single point whose distance from

the harness is 1 m with a height of 1m above the ground

plane. Under the test, radiated emissions may be missed

when the null of electric field causes at the measurement

position as shown in Fig. 2.

Scanning measurement method solves the problem [2]. It

measures the maximum value of electric field from 7 points

with moving the antenna along the harness at intervals of 250

mm between DUT and wire termination to avoid the weak

point of field. The measurement result is shown in Fig. 3.

The method provides precise to obtain radiated emissions

with long time for measurement as compared with CISPR25

test.

Proceedings of ISAP2016, Okinawa, Japan

Copyright ©2016 by IEICE

POS2-112

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mailto:matsuda-yasuyuki-dn@ynu.jpmailto:arai@ynu.ac.jpmailto:TAKANORI_UNOU@denso.co.jpmailto:ICHIRO_AKAHORI@denso.co.jpmailto:tanaka@mwf.co.jp

Fig. 3 Effectiveness of Scanning measurement method

3. 2-loops measurement method

We propose the 2-loop antenna measurement method. The

setup of the method is shown in Fig. 4. It consists of test

system and two loop antennas installed near DUT and wire

termination, respectively. The loop antenna is shorted to

metallic table at one end and connected to 50 Ohm feed port

at the other end. The size of both antennas is 150 mm × 150 mm. Proposed method obtains receiving voltage near DUT

and wire termination and picks up the sum of two probes as

the measurement value. The result of proposed and scanning

method is shown in Fig. 5. The voltage curve of proposed

method is gradually increased, whereas scanning one shown

as black line is flat for frequency. This difference is caused

by the antenna characteristic in each method. This difference

is compensated by adjusting measurement using antenna

factor (AF) as shown by blue line in Fig. 5.

Proposed method derives radiated emissions from

measured value by adjusting the difference of each method

and multiplying AF to convert into electric field value. Fig. 6

shows the deviation of each method in emission test for

actual automotive component. The method is possible to

evaluate within about 5 dB except for 30 MHz and 200 MHz

and achieve miniaturization and simplification compared

with scanning method.

4. Conclusion

This paper presented 2-loops measurement method to

remove scanning operation. The results show that the

proposed method provides measured data within about 5 dB

except for 30 MHz and 200 MHz compared with scanning

method. We demonstrated the effectiveness of proposed

method as the method of the radiated emissions test of

automotive component.

References

[1] “CISPR 25: Limits and methods of measurement of radio disturbance characteristics for protection of receivers used on board vehicles,” IEC, third ed., 2008.

[2] Takayuki Kubo, “CISPR25 Improvement correlation of measurement result of radiated emission,” KEC, vol. 217, pp. 45-51, April 2011.

(a) Top view

(b) Front view

Fig. 4 Setup of 2-loop antenna measurement method

Fig. 5 Compared scanning measurement method

with 2-loops measurement method

Fig. 6 Deviation between scanning method and 2-loop

antenna method for actual component

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